The main issue is the snow field there. Tried some other ideas on optimizing it today, no dice. Just can't get it to work without a high poly count (in the current case I think it was 256x256 (66k faces) or 128x128 (16k faces) subdivisions and having a large object pretty much always in view really tanks the performance. Also, I think the thing causing it to loading so badly is that it may be generating the noise at runtime. Probably should have saved them as images from the engine, similar to what I did with the tree mesh.
Did experiment with some other things in the video, mainly exporting the mesh and importing it as an actual mesh instead of an engine generated one (as that is heavy on the cpu), but it did not seem to help.